at worst the potential customer would use something else if they couldn't do what they wanted with your software, at best casual copying would spread the use of the program and actually lead to an increase in sales - and the ones which are losses can't be prevented by any means other than not writing the program in the first place.

and have the software only download the parts actually in use at a given time, keeping the code sections in a LRU cache and never providing the whole program at any given time; and second, encrypt the object files or bytecode when not in use. It will slow the software down (though not as much as you might think), but it will at least fulfill your brief.

I have tried this before because it seemed like a good idea, but it's always possible for people to dump the code while it's running.

This is definitely true, Notch/the Minecraft developer has a few good points on this too.

I have tried this before because it seemed like a good idea, but it's always possible for people to dump the code while it's running.

Don't roll your own crypto.

Don't roll your own crypto.

What is concerned here is protocol and whether it can be breached.

ok, please note that it is not software, it is the media content in question.

Message aka plain text=(

Storage medium serial No

+ No. of blocks on the storage medium

+ some password

+ media file binary

+ some other optional artifacts etc.,)

Yes, of course it can.

You're speaking about ONE check if hash1==hash2, at exactly that point replace the conditional jump with unconditional and you're done. Patch size will be either 1 or 5 bytes depending on the check.

Here you go, your "protection" gone poof.

option 1: convoluted code with multiple check points:

if hash1[0:N] == hash2[0:N]
do bunch of other stuff, decompress part of file etc., sheer enough code to discourage disassembly
if hash1[N+1:N+2N] == hash2[N+1:N+2N]
do bunch of other stuff, sheer enough code to discourage further disassembly,
further repeated checks.

option2:
hide validation code by performing simple encryption so that it can not be a disassembled.
during runtime: do a simple decryption so validation code only exist in memory in its unencrypted forum. Of course it is not safe but more work for diassembler.

Do you understand that Skype used option 2 and is now completely fully disassembled once people figured out this logic in the code? It only takes one OCD guy with enough time on his hands.

Do you realize that tools like reverse-analysers can take your convoluted machine code, convert it back to annotated AST representation of assembly code (using symbolic execution) and then reconstruct the entire "obfuscation" logic almost entirely automatically?

I.e. see work from https://www.blackhat.com/docs/eu-16/mat ... oaches.pdf

Do you understand that Skype used option 2 and is now completely fully disassembled once people figured out this logic in the code? It only takes one OCD guy with enough time on his hands.

Do you realize that tools like reverse-analysers can take your convoluted machine code, convert it back to annotated AST representation of assembly code (using symbolic execution) and then reconstruct the entire "obfuscation" logic almost entirely automatically?

I.e. see work from https://www.blackhat.com/docs/eu-16/mat ... oaches.pdf

+1 on what dozniak said.

Intel addresses the issue of option2 by attempting to encrypt the memory transport outside the cpu chip - Intel SGX - however there is still the problem of actually setting up a secure "enclave" as they call it and delivering your secret encrypted code into it so it can be decrypted & executed all while having memory accesses encrypted by SGX.... it is a crap shoot.

Now, if you have enough juice with Intel... you could have them encrypt your code using their LZH dictionary and run your code directly in the Intel Management Unit in every Intel chip since 2010...

If you want to really get some good copy protection going, go hire the guys who did the copy protection on Earthbound. There's still bits of it that we don't know what they do!